This basic research program will elucidate the in vivo roles of cytokines in tuberculosis. Developing and healing BCG lesions and tuberculin reactions will be produced in both rabbits and human beings. Tissue sections of these lesions will be made and quantitatively evaluated (a) for cell types (including surface markers), (b) for the amount of necrosis present (with an ocular grid), (c) for activated macrophages (using beta- galactosidase and acid phosphatase stains), (d) for bacilli and/or their antigens (with immunocytochemical techniques), (e) for cells producing reactive oxygen intermediates (H2O2), and (f) with in situ hybridization techniques for the mRNAs of interleukins 1, 2, 4 and 6, neutrophil (and lymphocyte) attractant/activating protein (NAP-1 or IL-8), macrophage chemoattractant/activating protein (MCP-1), interferon-gamma, tumor necrosis factors (TNF-alpha and beta), colony stimulating factor (GM/CSF), transforming growth factor (TNF-beta) and others. In time, cells containing receptors for some of these cytokines will also be identified. The objective is to determine which cytokines (and human T lymphocyte subtypes) play a role in in vivo-produced cell-mediated immunity (CMI) reactions (produced by BCG) and in in vivo-produced delayed type hypersensitivity (DTH) reactions (produced by tuberculin). BCG produces good CMI with relatively low levels of DTH, and tuberculin produces no CMI but can elicit a good DTH reaction, sometimes with caseous necrosis. Therefore, these studies will provide basic understanding of these two important immune reactions. Identification of in vivo cytokines associated specifically with CMI and specifically with DTH should help in the development of in vitro lymphocyte tests for selecting the best antigens to improve vaccines for tuberculosis, i.e., vaccines that produce the most favorable CMI:DTH ratio. In the host, such vaccines would expand T cell populations producing many activated macrophages (CMI) to a greater extent than they would expand T cell populations associated with caseous necrosis and liquefaction.